The present invention relates to an electric flash lamp unit with a light controlling circuit which can control an amount of flash light in accordance with a distance from a flash lamp to an object to be illuminated with the flash lamp.
There have been many proposals of the electric flash lamp units of this type. One of the flash lamp units proposed has a light control circuit in which light reflected from the object is photoelectric converted, the photoelectric converted signal is integrated by an integrating circuit including a capacitor, the flash is terminated when the integrated value reaches a given value. The light controlling circuit of the conventional flash lamp unit has a function like that of a memory for accumulatively storing the reflected light. Therefore, the light control circuit integrates not only the reflected light from the object but also the light from other flash light units, so that the flash lamp unit terminates the flash before an optimum exposure value is obtained. Japanese Patent Publication No. 28006/77 discloses a light control circuit without the integrating circuit to solve the above-mentioned problem. The light control circuit without the integrating circuit still involves a problem in a means to control the amount of light emitted from the flash lamp in accordance with a distance from the flash lamp to the object.